Abstract: A permutation class is a set of permutations closed under the natural combinatorial notion of subpermutation. The study of permutation classes, and in particular their enumeration has been an active area of research; spurred initially by the observation of strange coincidences in their enumerative sequences. The resolution, early this century, by Marcus and Tardos of the Stanley-Wilf conjecture has focused attention on the exponential growth rates of these classes. I will discuss the problem of characterizing the growth rates which can occur..
This talk will be accessible to graduate students.